Semiconductor device and method of embedding TSV semiconductor die within substrate for vertical interconnect in POP

ABSTRACT

A semiconductor device has a substrate with a first conductive layer over a surface of the substrate and a plurality of cavities exposing the first conductive layer. A first semiconductor die having conductive TSV is mounted into the cavities of the substrate. A first insulating layer is formed over the substrate and first semiconductor die and extends into the cavities to embed the first semiconductor die within the substrate. A portion of the first insulating layer is removed to expose the conductive TSV. A second conductive layer is formed over the conductive TSV. A portion of the first conductive layer is removed to form electrically common or electrically isolated conductive segments of the first conductive layer. A second insulating layer is formed over the substrate and conductive segments of the first conductive layer. A second semiconductor die is mounted over the substrate electrically connected to the second conductive layer.

FIELD OF THE INVENTION

The present invention relates in general to semiconductor devices and,more particularly, to a semiconductor device and method of embedding aTSV semiconductor die within a substrate for vertical interconnect in asemiconductor PoP.

BACKGROUND OF THE INVENTION

Semiconductor devices are commonly found in modern electronic products.Semiconductor devices vary in the number and density of electricalcomponents. Discrete semiconductor devices generally contain one type ofelectrical component, e.g., light emitting diode (LED), small signaltransistor, resistor, capacitor, inductor, and power metal oxidesemiconductor field effect transistor (MOSFET). Integrated semiconductordevices typically contain hundreds to millions of electrical components.Examples of integrated semiconductor devices include microcontrollers,microprocessors, charged-coupled devices (CCDs), solar cells, anddigital micro-mirror devices (DMDs).

Semiconductor devices perform a wide range of functions such as signalprocessing, high-speed calculations, transmitting and receivingelectromagnetic signals, controlling electronic devices, transformingsunlight to electricity, and creating visual projections for televisiondisplays. Semiconductor devices are found in the fields ofentertainment, communications, power conversion, networks, computers,and consumer products. Semiconductor devices are also found in militaryapplications, aviation, automotive, industrial controllers, and officeequipment.

Semiconductor devices exploit the electrical properties of semiconductormaterials. The atomic structure of semiconductor material allows itselectrical conductivity to be manipulated by the application of anelectric field or base current or through the process of doping. Dopingintroduces impurities into the semiconductor material to manipulate andcontrol the conductivity of the semiconductor device.

A semiconductor device contains active and passive electricalstructures. Active structures, including bipolar and field effecttransistors, control the flow of electrical current. By varying levelsof doping and application of an electric field or base current, thetransistor either promotes or restricts the flow of electrical current.Passive structures, including resistors, capacitors, and inductors,create a relationship between voltage and current necessary to perform avariety of electrical functions. The passive and active structures areelectrically connected to form circuits, which enable the semiconductordevice to perform high-speed calculations and other useful functions.

Semiconductor devices are generally manufactured using two complexmanufacturing processes, i.e., front-end manufacturing, and back-endmanufacturing, each involving potentially hundreds of steps. Front-endmanufacturing involves the formation of a plurality of die on thesurface of a semiconductor wafer. Each die is typically identical andcontains circuits formed by electrically connecting active and passivecomponents. The term “semiconductor die” as used herein refers to boththe singular and plural form of the word, and accordingly can refer toboth a single semiconductor device and multiple semiconductor devices.Back-end manufacturing involves singulating individual die from thefinished wafer and packaging the die to provide structural support andenvironmental isolation.

One goal of semiconductor manufacturing is to produce smallersemiconductor devices. Smaller devices typically consume less power,have higher performance, and can be produced more efficiently. Inaddition, smaller semiconductor devices have a smaller footprint, whichis desirable for smaller end products. A smaller die size can beachieved by improvements in the front-end process resulting in die withsmaller, higher density active and passive components. Back-endprocesses may result in semiconductor device packages with a smallerfootprint by improvements in electrical interconnection and packagingmaterials.

Semiconductor die are commonly stacked or otherwise require verticalz-direction interconnect capability. The vertical interconnect can beachieved with conductive through hole vias (THV) or conductive throughsilicon vias (TSV). The THVs and TSVs are formed by completely fillingvias formed through encapsulant or base semiconductor material withelectrically conductive material. The conductive vias are electricallyconnected to contact pads on the semiconductor die with redistributionlayers (RDL). When stacking semiconductor die, the TSV or THV of theupper die is electrically connected to the TSV or THV of the lower diewith bumps. The vertical interconnect provided by conductive TSV and THVtypically has a large form factor and package size. The largersemiconductor package size has a lower unit density on a substrate orPCB, which increases manufacturing cost.

SUMMARY OF THE INVENTION

A need exists for a simple and cost effective vertical electricalinterconnect for semiconductor PoP configurations. Accordingly, in oneembodiment, the present invention is a method of making a semiconductordevice comprising the steps of providing a substrate, forming a firstconductive layer over a surface of the substrate, forming a plurality ofcavities in the substrate to expose the first conductive layer, mountinga first semiconductor die having conductive TSV into the cavities of thesubstrate, forming a first insulating layer over the substrate and firstsemiconductor die extending into the cavities to embed the firstsemiconductor die within the substrate, removing a portion of the firstinsulating layer to expose the conductive TSV, forming a secondconductive layer over the conductive TSV, removing a portion of thefirst conductive layer to form electrically common or electricallyisolated conductive segments of the first conductive layer, and forminga second insulating layer over the substrate and conductive segments ofthe first conductive layer.

In another embodiment, the present invention is a method of making asemiconductor device comprising the steps of providing a first substratewith a first conductive layer and a plurality of cavities exposing thefirst conductive layer, mounting a first semiconductor die withconductive vias into the cavities of the first substrate, forming afirst insulating layer over the first substrate and first semiconductordie, removing a portion of the first insulating layer to expose theconductive vias, forming a second conductive layer over the conductivevias, removing a portion of the first conductive layer to formelectrically common or electrically isolated conductive segments of thefirst conductive layer, and forming a second insulating layer over thefirst substrate and conductive segments of the first conductive layer.

In another embodiment, the present invention is a method of making asemiconductor device comprising the steps of providing a first substratewith a first conductive layer and a plurality of cavities exposing thefirst conductive layer, mounting a first semiconductor die withconductive vias into the cavities of the first substrate, forming afirst insulating layer over the first substrate and first semiconductordie, forming a second conductive layer over the first insulating layerelectrically connected to the conductive vias, and removing a portion ofthe first conductive layer to form electrically common or electricallyisolated conductive segments of the first conductive layer.

In another embodiment, the present invention is a semiconductor devicecomprising a first substrate with a first conductive layer and aplurality of cavities exposing the first conductive layer. A firstsemiconductor die with conductive vias is mounted into the cavities ofthe first substrate. A first insulating layer is formed over the firstsubstrate and first semiconductor die. A second conductive layer isformed over the first insulating layer and electrically connected to theconductive vias. A portion of the first conductive layer is removed toform electrically common or electrically isolated conductive segments ofthe first conductive layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a printed circuit board (PCB) with different types ofpackages mounted to its surface;

FIGS. 2 a-2 c illustrate further detail of the representativesemiconductor packages mounted to the PCB;

FIGS. 3 a-3 c illustrate a semiconductor wafer with a plurality ofsemiconductor die separated by a saw street;

FIGS. 4 a-4 m illustrate a process of embedding a TSV semiconductor diewithin a substrate for vertical interconnect in a semiconductor PoP;

FIG. 5 illustrates the TSV semiconductor die within the substrate forvertical interconnect in the PoP;

FIGS. 6 a-6 b illustrate the semiconductor PoP with a secondsemiconductor die mounted to the embedded TSV semiconductor die;

FIG. 7 illustrates the second semiconductor die mounted to the embeddedTSV semiconductor die with bumps; and

FIG. 8 illustrates a substrate with stacked semiconductor die mounted tothe embedded TSV semiconductor die.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention is described in one or more embodiments in thefollowing description with reference to the figures, in which likenumerals represent the same or similar elements. While the invention isdescribed in terms of the best mode for achieving the invention'sobjectives, it will be appreciated by those skilled in the art that itis intended to cover alternatives, modifications, and equivalents as maybe included within the spirit and scope of the invention as defined bythe appended claims and their equivalents as supported by the followingdisclosure and drawings.

Semiconductor devices are generally manufactured using two complexmanufacturing processes: front-end manufacturing and back-endmanufacturing. Front-end manufacturing involves the formation of aplurality of die on the surface of a semiconductor wafer. Each die onthe wafer contains active and passive electrical components, which areelectrically connected to form functional electrical circuits. Activeelectrical components, such as transistors and diodes, have the abilityto control the flow of electrical current. Passive electricalcomponents, such as capacitors, inductors, resistors, and transformers,create a relationship between voltage and current necessary to performelectrical circuit functions.

Passive and active components are formed over the surface of thesemiconductor wafer by a series of process steps including doping,deposition, photolithography, etching, and planarization. Dopingintroduces impurities into the semiconductor material by techniques suchas ion implantation or thermal diffusion. The doping process modifiesthe electrical conductivity of semiconductor material in active devices,transforming the semiconductor material into an insulator, conductor, ordynamically changing the semiconductor material conductivity in responseto an electric field or base current. Transistors contain regions ofvarying types and degrees of doping arranged as necessary to enable thetransistor to promote or restrict the flow of electrical current uponthe application of the electric field or base current.

Active and passive components are formed by layers of materials withdifferent electrical properties. The layers can be formed by a varietyof deposition techniques determined in part by the type of materialbeing deposited. For example, thin film deposition can involve chemicalvapor deposition (CVD), physical vapor deposition (PVD), electrolyticplating, and electroless plating processes. Each layer is generallypatterned to form portions of active components, passive components, orelectrical connections between components.

The layers can be patterned using photolithography, which involves thedeposition of light sensitive material, e.g., photoresist, over thelayer to be patterned. A pattern is transferred from a photomask to thephotoresist using light. In one embodiment, the portion of thephotoresist pattern subjected to light is removed using a solvent,exposing portions of the underlying layer to be patterned. In anotherembodiment, the portion of the photoresist pattern not subjected tolight, the negative photoresist, is removed using a solvent, exposingportions of the underlying layer to be patterned. The remainder of thephotoresist is removed, leaving behind a patterned layer. Alternatively,some types of materials are patterned by directly depositing thematerial into the areas or voids formed by a previous deposition/etchprocess using techniques such as electroless and electrolytic plating.

Depositing a thin film of material over an existing pattern canexaggerate the underlying pattern and create a non-uniformly flatsurface. A uniformly flat surface is required to produce smaller andmore densely packed active and passive components. Planarization can beused to remove material from the surface of the wafer and produce auniformly flat surface. Planarization involves polishing the surface ofthe wafer with a polishing pad. An abrasive material and corrosivechemical are added to the surface of the wafer during polishing. Thecombined mechanical action of the abrasive and corrosive action of thechemical removes any irregular topography, resulting in a uniformly flatsurface.

Back-end manufacturing refers to cutting or singulating the finishedwafer into the individual die and then packaging the die for structuralsupport and environmental isolation. To singulate the die, the wafer isscored and broken along non-functional regions of the wafer called sawstreets or scribes. The wafer is singulated using a laser cutting toolor saw blade. After singulation, the individual die are mounted to apackage substrate that includes pins or contact pads for interconnectionwith other system components. Contact pads formed over the semiconductordie are then connected to contact pads within the package. Theelectrical connections can be made with solder bumps, stud bumps,conductive paste, or wirebonds. An encapsulant or other molding materialis deposited over the package to provide physical support and electricalisolation. The finished package is then inserted into an electricalsystem and the functionality of the semiconductor device is madeavailable to the other system components.

FIG. 1 illustrates electronic device 50 having a chip carrier substrateor printed circuit board (PCB) 52 with a plurality of semiconductorpackages mounted on its surface. Electronic device 50 can have one typeof semiconductor package, or multiple types of semiconductor packages,depending on the application. The different types of semiconductorpackages are shown in FIG. 1 for purposes of illustration.

Electronic device 50 can be a stand-alone system that uses thesemiconductor packages to perform one or more electrical functions.Alternatively, electronic device 50 can be a subcomponent of a largersystem. For example, electronic device 50 can be part of a cellularphone, personal digital assistant (PDA), digital video camera (DVC), orother electronic communication device. Alternatively, electronic device50 can be a graphics card, network interface card, or other signalprocessing card that can be inserted into a computer. The semiconductorpackage can include microprocessors, memories, application specificintegrated circuits (ASIC), logic circuits, analog circuits, RFcircuits, discrete devices, or other semiconductor die or electricalcomponents. Miniaturization and weight reduction are essential for theseproducts to be accepted by the market. The distance betweensemiconductor devices must be decreased to achieve higher density.

In FIG. 1, PCB 52 provides a general substrate for structural supportand electrical interconnect of the semiconductor packages mounted on thePCB. Conductive signal traces 54 are formed over a surface or withinlayers of PCB 52 using evaporation, electrolytic plating, electrolessplating, screen printing, or other suitable metal deposition process.Signal traces 54 provide for electrical communication between each ofthe semiconductor packages, mounted components, and other externalsystem components. Traces 54 also provide power and ground connectionsto each of the semiconductor packages.

In some embodiments, a semiconductor device has two packaging levels.First level packaging is a technique for mechanically and electricallyattaching the semiconductor die to an intermediate carrier. Second levelpackaging involves mechanically and electrically attaching theintermediate carrier to the PCB. In other embodiments, a semiconductordevice may only have the first level packaging where the die ismechanically and electrically mounted directly to the PCB.

For the purpose of illustration, several types of first level packaging,including bond wire package 56 and flipchip 58, are shown on PCB 52.Additionally, several types of second level packaging, including ballgrid array (BGA) 60, bump chip carrier (BCC) 62, dual in-line package(DIP) 64, land grid array (LGA) 66, multi-chip module (MCM) 68, quadflat non-leaded package (QFN) 70, and quad flat package 72, are shownmounted on PCB 52. Depending upon the system requirements, anycombination of semiconductor packages, configured with any combinationof first and second level packaging styles, as well as other electroniccomponents, can be connected to PCB 52. In some embodiments, electronicdevice 50 includes a single attached semiconductor package, while otherembodiments call for multiple interconnected packages. By combining oneor more semiconductor packages over a single substrate, manufacturerscan incorporate pre-made components into electronic devices and systems.Because the semiconductor packages include sophisticated functionality,electronic devices can be manufactured using cheaper components and astreamlined manufacturing process. The resulting devices are less likelyto fail and less expensive to manufacture resulting in a lower cost forconsumers.

FIGS. 2 a-2 c show exemplary semiconductor packages. FIG. 2 aillustrates further detail of DIP 64 mounted on PCB 52. Semiconductordie 74 includes an active region containing analog or digital circuitsimplemented as active devices, passive devices, conductive layers, anddielectric layers formed within the die and are electricallyinterconnected according to the electrical design of the die. Forexample, the circuit can include one or more transistors, diodes,inductors, capacitors, resistors, and other circuit elements formedwithin the active region of semiconductor die 74. Contact pads 76 areone or more layers of conductive material, such as aluminum (Al), copper(Cu), tin (Sn), nickel (Ni), gold (Au), or silver (Ag), and areelectrically connected to the circuit elements formed withinsemiconductor die 74. During assembly of DIP 64, semiconductor die 74 ismounted to an intermediate carrier 78 using a gold-silicon eutecticlayer or adhesive material such as thermal epoxy or epoxy resin. Thepackage body includes an insulative packaging material such as polymeror ceramic. Conductor leads 80 and bond wires 82 provide electricalinterconnect between semiconductor die 74 and PCB 52. Encapsulant 84 isdeposited over the package for environmental protection by preventingmoisture and particles from entering the package and contaminating die74 or bond wires 82.

FIG. 2 b illustrates further detail of BCC 62 mounted on PCB 52.Semiconductor die 88 is mounted over carrier 90 using an underfill orepoxy-resin adhesive material 92. Bond wires 94 provide first levelpackaging interconnect between contact pads 96 and 98. Molding compoundor encapsulant 100 is deposited over semiconductor die 88 and bond wires94 to provide physical support and electrical isolation for the device.Contact pads 102 are formed over a surface of PCB 52 using a suitablemetal deposition process such as electrolytic plating or electrolessplating to prevent oxidation. Contact pads 102 are electricallyconnected to one or more conductive signal traces 54 in PCB 52. Bumps104 are formed between contact pads 98 of BCC 62 and contact pads 102 ofPCB 52.

In FIG. 2 c, semiconductor die 58 is mounted face down to intermediatecarrier 106 with a flipchip style first level packaging. Active region108 of semiconductor die 58 contains analog or digital circuitsimplemented as active devices, passive devices, conductive layers, anddielectric layers formed according to the electrical design of the die.For example, the circuit can include one or more transistors, diodes,inductors, capacitors, resistors, and other circuit elements withinactive region 108. Semiconductor die 58 is electrically and mechanicallyconnected to carrier 106 through bumps 110.

BGA 60 is electrically and mechanically connected to PCB 52 with a BGAstyle second level packaging using bumps 112. Semiconductor die 58 iselectrically connected to conductive signal traces 54 in PCB 52 throughbumps 110, signal lines 114, and bumps 112. A molding compound orencapsulant 116 is deposited over semiconductor die 58 and carrier 106to provide physical support and electrical isolation for the device. Theflipchip semiconductor device provides a short electrical conductionpath from the active devices on semiconductor die 58 to conductiontracks on PCB 52 in order to reduce signal propagation distance, lowercapacitance, and improve overall circuit performance. In anotherembodiment, the semiconductor die 58 can be mechanically andelectrically connected directly to PCB 52 using flipchip style firstlevel packaging without intermediate carrier 106.

FIG. 3 a shows a semiconductor wafer 120 with a base substrate material122, such as silicon, germanium, gallium arsenide, indium phosphide, orsilicon carbide, for structural support. A plurality of semiconductordie or components 124 is formed on wafer 120 separated by a non-active,inter-die wafer area or saw street 126 as described above. Saw street126 provides cutting areas to singulate semiconductor wafer 120 intoindividual semiconductor die 124. In one embodiment, semiconductor die124 may have dimensions ranging from 2×2 millimeters (mm) to 15×15 mm.

FIG. 3 b shows a cross-sectional view of a portion of semiconductorwafer 120. Each semiconductor die 124 has a back surface 128 and activesurface 130 containing analog or digital circuits implemented as activedevices, passive devices, conductive layers, and dielectric layersformed within the die and electrically interconnected according to theelectrical design and function of the die. For example, the circuit mayinclude one or more transistors, diodes, and other circuit elementsformed within active surface 130 to implement analog circuits or digitalcircuits, such as digital signal processor (DSP), ASIC, memory, or othersignal processing circuit. Semiconductor die 124 may also containintegrated passive devices (IPDs), such as inductors, capacitors, andresistors, for RF signal processing. In one embodiment, semiconductordie 124 is a flipchip type die.

A plurality of vias is formed into active surface 130 and throughsemiconductor wafer 120 using mechanical drilling, laser drilling, ordeep reactive ion etching (DRIE). The vias are filled with Al, Cu, Sn,Ni, Au, Ag, titanium (Ti), tungsten (W), poly-silicon, or other suitableelectrically conductive material using electrolytic plating, electrolessplating process, or other suitable metal deposition process to formz-direction conductive through silicon vias (TSV) 132 embedded withinsemiconductor die 124.

An electrically conductive layer 134 is formed over active surface 130using PVD, CVD, electrolytic plating, electroless plating process, orother suitable metal deposition process. Conductive layer 134 can be oneor more layers of Al, Cu, Sn, Ni, Au, Ag, or other suitable electricallyconductive material. Conductive layer 134 operates as contact padselectrically connected to the circuits on active surface 130. Contactpads 134 can be disposed side-by-side a first distance from the edge ofsemiconductor die 124, as shown in FIG. 3 b. Alternatively, contact pads134 can be offset in multiple rows such that a first row of contact padsis disposed a first distance from the edge of the die, and a second rowof contact pads alternating with the first row is disposed a seconddistance from the edge of the die.

An electrically conductive bump material is deposited over contact pads134 using an evaporation, electrolytic plating, electroless plating,ball drop, or screen printing process. The bump material can be Al, Sn,Ni, Au, Ag, Pb, Bi, Cu, solder, and combinations thereof, with anoptional flux solution. For example, the bump material can be eutecticSn/Pb, high-lead solder, or lead-free solder. The bump material isbonded to contact pads 134 using a suitable attachment or bondingprocess. In one embodiment, the bump material is reflowed by heating thematerial above its melting point to form spherical balls or bumps 136.In some applications, bumps 136 are reflowed a second time to improveelectrical contact to contact pads 134. Bumps 136 can also becompression bonded to contact pads 134. Bumps 136 represent one type ofinterconnect structure that can be formed over contact pads 134. Theinterconnect structure can also use stud bump, micro bump, or otherelectrical interconnect.

In FIG. 3 c, semiconductor wafer 120 is singulated through saw street126 using a saw blade or laser cutting tool 138 into individual TSVsemiconductor die 124.

FIGS. 4 a-4 m illustrate, in relation to FIGS. 1 and 2 a-2 c, a processof embedding a TSV semiconductor die within a substrate for verticalinterconnect in a semiconductor PoP. FIG. 4 a shows an electricallyconductive layer 140 formed over a surface of base insulating layer 142.Conductive layer 140 can be one or more layers of Al, Cu, Sn, Ni, Au,Ag, or other suitable electrically conductive material. The insulatinglayer 142 can be a laminate substrate made with benzocyclobutene (BCB),polyimide (PI), polybenzoxazoles (PBO), acrylic resin, or other suitabledielectric material. In one embodiment, conductive layer 140 and baseinsulating layer 142 constitute a copper clad laminate substrate (CCL)144. A portion of insulating layer 142 is removed by an etching processto form cavities or openings 145 for subsequent TSV semiconductor dieattach, as shown in FIG. 4 b.

In FIG. 4 c, the TSV semiconductor die 124 from FIGS. 3 a-3 c aremounted within cavities 145 using a pick and place operation with activesurface 130 oriented toward conductive layer 140. FIG. 4 d shows TSVsemiconductor die 124 mounted within cavities 145 of CLL substrate 144and electrically connected to conductive layer 140. In one embodiment,TSV semiconductor die 124 are positioned within cavities 145 so thatback surface 128 is substantially coplanar with a top surface ofinsulating layer 142. Alternatively, back surface 128 can be positionedabove or below the top surface of insulating layer 142.

In FIG. 4 e, an insulating layer 146 is formed over insulating layer 142and back surface 128 of semiconductor die 124 using PVD, CVD, printing,spin coating, spray coating, sintering or thermal oxidation. Theinsulating layer 146 contains one or more layers of solder resist, SiO2,Si3N4, SiON, Ta2O5, Al2O3, or other material having similar insulatingand structural properties. In one embodiment, insulating layer 146 has athickness of 10-20 micrometers (μm) over back surface 128 and insulatinglayer 142. The insulating layer 146 extends into cavities 145 along theside surfaces of semiconductor die 124 to conductive layer 140 to embedthe TSV semiconductor die within CCL substrate 144. A portion ofinsulating layer 146 is removed by a patterning, developing, and etchingprocess to form openings 147 and expose back surface 128 and conductiveTSV 132.

In FIG. 4 f, an electrically conductive layer 148 is conformally appliedover openings 147 in insulating layer 146 using patterning with PVD,CVD, sputtering, electrolytic plating, electroless plating process, orother suitable metal deposition process. Conductive layer 148 can be oneor more layers of Al, Cu, Sn, Ni, Au, Ag, Ti, TiW, or other suitableelectrically conductive material. Conductive layer 148 is conformallyapplied on the sidewalls of openings 147 to follow a contour ofinsulating layer 146. Conductive layer 148 is thus recessed withininsulating layer 146 with an open central portion 149 above the bottomsurface of the conductive layer due to the thickness of the insulatinglayer. Conductive layer 148 is electrically connected to conductive TSV132.

In FIG. 4 g, an insulating layer 150 is formed over insulating layer146. Likewise, an insulating layer 152 is formed over conductive layer140. In one embodiment, insulating layers 150 and 152 can be aphoto-sensitive dry film layer suitable for patterning and developing,such as photo resist or polymer material.

In FIG. 4 h, a photo-mask layer 154 is formed over insulating layer 152and conductive layer 140 for patterning and developing the insulatinglayer in order to remove a portion of the conductive layer. Photo-masklayer 154 is removed in FIG. 4 i and the remaining portion of insulatinglayer 152 is removed in FIG. 4 j to leave conductive layer 140 etchedwith the desired pattern containing a plurality of conductive segments140 a-140 e for electrical connection to semiconductor die 124 throughbumps 136. The post-etched conductive segments 140 a-140 e areelectrically common or electrically isolated depending on the design andfunction of semiconductor die 124.

In FIG. 4 k, an insulating or passivation layer 156 is formed overconductive layer 140 and insulating layer 142 using PVD, CVD, printing,spin coating, spray coating, sintering or thermal oxidation. Theinsulating layer 156 contains one or more layers of solder resist,silicon dioxide (SiO2), silicon nitride (Si3N4), silicon oxynitride(SiON), tantalum pentoxide (Ta2O5), aluminum oxide (Al2O3), or othermaterial having similar insulating and structural properties. A portionof insulating layer 156 is removed by a patterning and developingprocess to expose conductive layer 140, as shown in FIG. 41. Theinsulating layer 150 is also removed to expose insulating layer 146 andconductive layer 148. The exposed conductive layers 146 and 148 can betreated with copper on organic solderability preservative (CuOSP) orNi/Au.

In FIG. 4 m, an electrically conductive bump material is deposited overconductive segments 140 a-140 e using an evaporation, electrolyticplating, electroless plating, ball drop, or screen printing process. Thebump material can be Al, Sn, Ni, Au, Ag, Pb, Bi, Cu, solder, andcombinations thereof, with an optional flux solution. For example, thebump material can be eutectic Sn/Pb, high-lead solder, or lead-freesolder. The bump material is bonded to conductive segments 140 a-140 eusing a suitable attachment or bonding process. In one embodiment, thebump material is reflowed by heating the material above its meltingpoint to form spherical balls or bumps 158. In some applications, bumps158 are reflowed a second time to improve electrical contact toconductive segments 140 a-140 e. Bumps 158 can also be compressionbonded to conductive segments 140 a-140 e. Bumps 158 represent one typeof interconnect structure that can be formed over conductive segments140 a-140 e. The interconnect structure can also use stud bump, microbump, or other electrical interconnect.

The semiconductor device is singulated through insulating layers 142,146, and 156 between semiconductor die 124 using a saw blade or lasercutting tool 160 to separate individual semiconductor packages 162.

FIG. 5 shows semiconductor package 162 after singulation. The TSVsemiconductor die 124 is embedded within CCL substrate 144 andelectrically connected through bumps 136 and conductive segments 140a-140 e to bumps 158 for external interconnect from a bottom side ofsemiconductor package 162. Semiconductor die 124 is also electricallyconnected through conductive TSV 132 within the die and conductive layer148 for external interconnect from a topside of semiconductor package162. The vertical interconnect provided by conductive TSV 132 andconductive layers 140 and 148 achieve a smaller form factor to reducethe package footprint. The smaller size of semiconductor package 162gives a high unit density on a substrate or PCB, which reducesmanufacturing cost.

FIG. 6 a shows a semiconductor die 164 having an active surface 170containing analog or digital circuits implemented as active devices,passive devices, conductive layers, and dielectric layers formed withinthe die and electrically interconnected according to the electricaldesign and function of the die. For example, the circuit may include oneor more transistors, diodes, and other circuit elements formed withinactive surface 170 to implement analog circuits or digital circuits,such as DSP, ASIC, memory, or other signal processing circuit.Semiconductor die 164 may also contain IPDs, such as inductors,capacitors, and resistors, for RF signal processing. In one embodiment,semiconductor die 164 is a flipchip type die.

An electrically conductive layer 172 is formed over active surface 170using PVD, CVD, electrolytic plating, electroless plating process, orother suitable metal deposition process. Conductive layer 172 can be oneor more layers of Al, Cu, Sn, Ni, Au, Ag, or other suitable electricallyconductive material. Conductive layer 172 operates as contact padselectrically connected to the circuits on active surface 170. Contactpads 172 can be disposed side-by-side a first distance from the edge ofsemiconductor die 164. Alternatively, contact pads 172 can be offset inmultiple rows such that a first row of contact pads is disposed a firstdistance from the edge of the die, and a second row of contact padsalternating with the first row is disposed a second distance from theedge of the die.

A plurality of non-collapsible non-fusible conductive posts 174 isformed over contact pads 172. Fusible bumps 176 are formed overconductive posts 174. The combination of conductive posts 174 and bumps176 constitute a composite interconnect structure with thenon-collapsible conductive posts providing a fixed vertical offset andthe bumps providing a fusible bonding surface. Semiconductor die 164 ismounted to semiconductor package 162 in a package-on-package (PoP)configuration 178 with conductive posts 174 extending partially intoopen portion 149 and bumps 176 electrically connected to conductivelayer 148, as shown in FIG. 6 b. In one embodiment, semiconductor die164 is a memory die and semiconductor die 124 is a baseband signalprocessing die. Conductive posts 174 give vertical offset forsemiconductor die 164 to account for the thickness of insulating layer146 and the recessed conductive layer 148. Semiconductor die 164 iselectrically connected through conductive posts 174, bumps 176,conductive layer 148, and conductive TSV 132 to semiconductor die 124.Semiconductor die 164 is also electrically connected to conductive layer140 and bumps 158 for external interconnect. An underfill material 180,such as epoxy resin, is deposited between semiconductor die 164 andsemiconductor package 162. Semiconductor PoP 178 exhibits reducedsusceptibility to warpage and high surface mount technology (SMT) yieldwith a small form factor. Semiconductor PoP 178 uses a simplifiedassembly process for higher productivity in terms of manufacturing unitsper hour (UPH) at lower production cost for the semiconductor PoP.

FIG. 7 shows an embodiment of semiconductor PoP 182, similar to FIG. 6b, with fusible bumps 184 between contact pads 172 of semiconductor die164 and conductive layer 148. Bumps 184 are sufficiently large to makeelectrical connection with the recessed conductive layer 148, whileproviding vertical offset for semiconductor die 164.

FIG. 8 shows an embodiment of semiconductor PoP 200, similar to FIG. 6b, with a portion of insulating layer 146 removed to expose back surface128 of semiconductor die 124. Semiconductor die 202 has an activesurface 204 containing analog or digital circuits implemented as activedevices, passive devices, conductive layers, and dielectric layersformed within the die and electrically interconnected according to theelectrical design and function of the die. For example, the circuit mayinclude one or more transistors, diodes, and other circuit elementsformed within active surface 204 to implement analog circuits or digitalcircuits, such as DSP, ASIC, memory, or other signal processing circuit.Semiconductor die 202 may also contain IPDs, such as inductors,capacitors, and resistors, for RF signal processing. Semiconductor die202 is mounted to substrate 206 with die attach adhesive 208. Thecontact pads of semiconductor die 202 are electrically connected toconductive traces 210 formed on substrate 206 with bond wires 212.

Semiconductor die 214 has an active surface 216 containing analog ordigital circuits implemented as active devices, passive devices,conductive layers, and dielectric layers formed within the die andelectrically interconnected according to the electrical design andfunction of the die. For example, the circuit may include one or moretransistors, diodes, and other circuit elements formed within activesurface 216 to implement analog circuits or digital circuits, such asDSP, ASIC, memory, or other signal processing circuit. Semiconductor die214 may also contain IPDs, such as inductors, capacitors, and resistors,for RF signal processing. Semiconductor die 214 is mounted tosemiconductor die 202 with die attach adhesive 218. The contact pads ofsemiconductor die 214 are electrically connected to conductive traces210 formed on substrate 206 with bond wires 220.

An encapsulant or molding compound 222 is deposited over semiconductordie 202 and 214 and substrate 206 using a paste printing, compressivemolding, transfer molding, liquid encapsulant molding, vacuumlamination, spin coating, or other suitable applicator. Encapsulant 222can be polymer composite material, such as epoxy resin with filler,epoxy acrylate with filler, or polymer with proper filler. Encapsulant222 is non-conductive and environmentally protects the semiconductordevice from external elements and contaminants.

Substrate 206, with stacked semiconductor die 202 and 214 enclosed byencapsulant 222, is mounted to semiconductor package 162 with bumps 224extending partially into open portion 149 to electrically connect toconductive layer 148. The exposed back surface 128 provides enhancedheat dissipation for semiconductor die 124.

While one or more embodiments of the present invention have beenillustrated in detail, the skilled artisan will appreciate thatmodifications and adaptations to those embodiments may be made withoutdeparting from the scope of the present invention as set forth in thefollowing claims.

What is claimed:
 1. A method of making a semiconductor device,comprising: providing a substrate; forming a first conductive layer overa surface of the substrate; forming a cavity in the substrate to exposethe first conductive layer; disposing a first semiconductor dieincluding a conductive via into the cavity of the substrate with theconductive via electrically connected to the first conductive layer;forming an insulating layer over the substrate and first semiconductordie and extending into the cavity to embed the first semiconductor diewithin the substrate; removing a portion of the insulating layer to theconductive via; forming a second conductive layer over the conductivevia; and removing a portion of the first conductive layer while leavingconductive segments of the first conductive layer electrically connectedto the first semiconductor die to provide a vertical interconnectthrough the conductive via to the second conductive layer, the verticalinterconnect disposed within a footprint of the first semiconductor die.2. The method of claim 1, further including forming a plurality of bumpsover the conductive segments of the first conductive layer.
 3. Themethod of claim 1, further including singulating the substrate toseparate the first semiconductor die.
 4. The method of claim 1, furtherincluding conformally applying the second conductive layer to follow acontour of the insulating layer into the removed portion of theinsulating layer.
 5. The method of claim 1, further including disposinga second semiconductor die over the substrate electrically connected tothe second conductive layer.
 6. The method of claim 5, furtherincluding: forming non-collapsible conductive posts over contact pads ofthe second semiconductor die; and forming fusible bumps over thenon-collapsible conductive posts.
 7. A method of making a semiconductordevice, comprising: providing a first substrate; forming a firstconductive layer over the first substrate; forming a cavity in the firstsubstrate to expose the first conductive layer; disposing a firstsemiconductor die including a conductive via into the cavity of thefirst substrate with a first surface of the first semiconductor dieoriented towards the first conductive layer; forming an insulating layerover the first substrate and a second surface of the first semiconductordie opposite the first surface with the insulating layer extending intothe cavity to embed the first semiconductor die within the firstsubstrate; forming a second conductive layer into an opening of theinsulating layer to contact the conductive via; and removing a portionof the first conductive layer while leaving conductive segments of thefirst conductive layer electrically connected to the first semiconductordie to provide a vertical interconnect through the conductive via to thesecond conductive layer.
 8. The method of claim 7, further includingforming an interconnect structure over the conductive segments of thefirst conductive layer.
 9. The method of claim 7, further includingconformally applying the second conductive layer to follow a contour ofthe opening of the insulating layer.
 10. The method of claim 7, furtherincluding disposing a second semiconductor die over the first substrateelectrically connected to the second conductive layer.
 11. The method ofclaim 10, further including forming an interconnect structure overcontact pads of the second semiconductor die.
 12. The method of claim 7,further including: providing a second substrate; disposing a secondsemiconductor die over the first substrate; disposing a thirdsemiconductor die over the second semiconductor die; and disposing thesecond substrate over the second conductive layer.
 13. A method ofmaking a semiconductor device, comprising: providing a first substrate;forming a first conductive layer over the first substrate; forming acavity in the first substrate extending to expose the first conductivelayer; disposing a first semiconductor die including a conductive viainto the cavity of the first substrate; forming a first insulating layerover a top surface of the first substrate opposite the first conductivelayer and over the first semiconductor die and extending into the cavityto embed the first semiconductor die within the first substrate; forminga second conductive layer over the first insulating layer electricallyconnected to the conductive via; and removing a portion of the firstconductive layer while leaving conductive segments of the firstconductive layer electrically connected to the first semiconductor dieto provide a vertical interconnect through the conductive via to thesecond conductive layer.
 14. The method of claim 13, further includingforming a second insulating layer over the first substrate andconductive segments of the first conductive layer.
 15. The method ofclaim 13, further including forming an interconnect structure over theconductive segments of the first conductive layer.
 16. The method ofclaim 13, further including conformally applying the second conductivelayer to follow a contour of the first insulating layer.
 17. The methodof claim 13, further including disposing a second semiconductor die overthe first substrate electrically connected to the second conductivelayer.
 18. The method of claim 13, further including: providing a secondsubstrate; disposing a second semiconductor die over the firstsubstrate; disposing a third semiconductor die over the secondsemiconductor die; and disposing the second substrate over the secondconductive layer.